| In strong earthquake area,the tunnel crossing fault fracture zone is often seriously damaged.However,at present,researches on the dynamic response characteristics of tunnel structure in strong earthquake zone are limited under a PGA of 0.4g,and there are few researches on the crossing of inactive faults with a PGA as 0.6g.When the PGA is 0.6g and the fault zone width is large,it is particularly important to study the dynamic response of the tunnel crossing the fault interface.The research on the dynamic response analysis and control technology of the tunnel crossing the fault interface in strong earthquake area is helpful to improve the seismic performance and stability of the tunnel structure crossing the fault interface under the action of ground motion.In this paper,taking a tunnel crossing fault in Central Asia as an example,the dynamic response law and control technology of tunnel crossing fault interface are studied by using the methods of literature research,mechanical model establishment,theoretical derivation and numerical simulation.The results can be used in the seismic design of similar tunnel projects.The main research contents and results of this paper are as follows:(1)By establishing the mechanical model of fault interface,analyzing theoretically the mechanical model and establishing the relationship between the interface strength,the surrounding rock stiffness and the displacement transfer coefficient,the results show that the improvement of the interface strength and the surrounding rock stiffness is conductive to the stability of the surrounding rock mass on both sides of the fault interface under strong earthquake.(2)The dynamic response of tunnel structure crossing the interface of inactive fault is studied.The dynamic response law of tunnel structure under different combination of surrounding rock on both sides of fault interface and different dip angles of fault interface is studied.The results show that with the decrease of surrounding rock parameters on both sides of the fault interface,the stress response,relative displacement and deformation of the tunnel structure increase.Meanwhile,with the increase of the dip Angle of the fault interface,the stress response at the vault and invert of the tunnel structure at the fault interface increases,and the relative displacement and deformation of the tunnel structure increase.The tunnel structure should be fortification against earthquake at 4 times the tunnel diameter in the better surrounding rock on both sides of the fault interface and 5 times the tunnel diameter in the fault zone.(3)The control technology of tunnel crossing fault interface is studied.The dynamic response of tunnel structure under different section lining width,different thickness shock absorption layer and different lining stiffness is compared and analyzed,and the results show that as the width of segmental lining decreases,the stress on the tunnel decreases,but the displacement increases.And it is more appropriate when the width of segment lining is 6m.Meanwhile,when the thickness of the damping layer increases,the stress,displacement and deformation of the tunnel structure decrease,and the thickness of the damping layer should be20 cm.The force of rigid support is larger,but the displacement and deformation are smaller than that of flexible support.What’s more,the setting methods and conditions of different control technologies are refined to provide reference for tunnel engineering construction in strong earthquake areas. |
